Hydraulic auxiliary drive for vehicles

ABSTRACT

A hydraulic auxiliary drive system which derives power from the driven wheels of a vehicle and applies that power to the normally non-driven wheels of the vehicle, or of a trailer towed by the vehicle. The self-contained closed system includes hydraulic pump units which are simply bolted on the existing driven wheel mountings, and hydraulic motors which are bolted on the wheels to be driven. An actuating valve engages or disengages the drive and selection means is provided for applying the auxiliary power to the vehicle or trailer, as required. When not in use the system does not affect normal performance of the vehicle.

United States Patent 1 Finney [54] HYDRAULIC AUXILIARY DRIVE FORVEHICLES [76] Inventor: Frank E. Finney, 2744 Felicita Rd.,

Escondido, Calif. 92025 [22] Filed: June 10, 1971 [21] Appl. No.:151,722

[52] 0.5. CI 180/66 R, 180/44 F [51] Int. Cl 860k 7/00, B601: 23/08 [58]Field of Search 180/66 R, 66 F, 44 F, 180/44 M, 10

[56] References Cited UNITED STATES PATENTS 3,532,177 10/1970 Herrman180/66 R 3,415,334 12/1968 Vriend 180/66 R 2,650,573 9/1953l-lickman..... 180/66 R 3,075,598 1/1963 Pheneger 180/66 R X 3,430,7223/1969 Budzich 180/66 R X 3,447,619 6/1969 Nodwell et al 180/66 R X2,516,662 7/1950 Vickers et al 180/66 R July 24, 1973 FOREIGN PATENTS ORAPPLICATIONS 1,133,019 11/1956 France 180/66R Primary Examiner-RobertSpar Attorney-Carl R. Brown and Neil F. Martin ABSTRACT A hydraulicauxiliary drive system which derives power from the driven wheels of avehicle and applies that power to the normally non-driven wheels of thevehicle, or of a trailer towed by the vehicle. The selfcontained closedsystem includes hydraulic pump units which are simply bolted on theexisting driven wheel mountings, and hydraulic motors which are boltedon the wheels to be driven. An actuating valve engages or disengages thedrive and selection means is provided for applying the auxiliary powerto the vehicle or trailer, as required. When not in use the system doesnot affect normal performance of the vehicle.

10 Claims, 4 Drawing Figures HYDRAULIC AUXILIARY DRIVE FOR VEHICLESBACKGROUND OF THE INVENTION In vehicles in which all wheels are requiredto be driven at certain times for added traction, various means havebeen devised for applying power to the normally non-driven wheels. Oneparticular type of four wheel drive vehicle uses an elaboratetransmission to shift between two and four wheel power positions. Somevehicles of this basic type necessitate stopping the vehicle andengaging the drive externally. When the four wheel drive is not in use,the added mechanism causes an undesirable drag on the power of thevehicle. Certain low speed vehicles, particularly for heavy hauling ormaterial handling, have been built with individual hydraulic motors ineach wheel, powered from a common pressure source. This results in aspecialized and expensive vehicle with a limited field of use.

SUMMARY OF THE INVENTION The auxiliary drive system described herein isadaptable to many existing vehicles with a pair of driven wheels, andprovides power for selectively driving the other wheels of the vehicle,or the wheels of a trailer towed by the vehicle. A hydraulic pump isbolted on to each driven wheel, using the existing mounting and a simpleadapter. A compatible hydraulic motor is bolted on to each wheel to bedriven and coupled to one of the pumps with a closed fluid system. Eachpump and motor has a simple fluid operated mechanism for positiveengagement with or disengagement from the respective wheel, themechanism being actuated by a control valve accessible to the vehicledriver. When not in use the auxiliary drive is completely disconnectedand stationary and does not impose any drag on the vehicle, or interferewith normal performance.

The primary object of this invention, therefore, is to provide a new andimproved hydraulic auxiliary drive for vehicles.

It is another object of this invention to provide a new and improvedhydraulic auxiliary drive which is adaptable to existing vehicles with aminimum of modification and without interfering with normal operation.

It is another object of this invention to provide a new and improvedhydraulic auxiliary drive having a selfcontained and closed fluidsystem, with internal fluid actuated means for engaging and disengagingthe drive.

It is another object of this invention to provide a new and improvedhydraulic auxiliary drive, with means for selectively applying auxiliarypower to the vehicle or to a trailer towed by the vehicle.

Other objects and many advantages of this invention will become moreapparent upon a reading of the following detailed description whereinlike reference nu merals designate like parts throughoutand in which:

FIG. 1 is a diagrammatic top plan view of the system installed on avehicle chassis.

FIG. 2 is an enlarged diametrical section of a driven wheel,illustrating the hydraulic pump mounting.

FIG. 3 is a further enlarged sectional view, similar to a portion ofFIG. 2, but showing the drive engaging means for the hydraulic motorunit.

FIG. 4 is an enlarged view, partially cut away, of the drive controlvalve.

DESCRIPTION OF THE PREFERRED EMBODIMENT A typical vehicle chassis 10 isshown in diagrammatic form in FIG. 1, with rear wheels 12 coupledthrough a differential unit 14 to a drive shaft 16, and non-driven frontwheels 18. In FIG. 2, the rear wheel structure is shown to include anaxle 20 to which is secured a brake drum 22, the axle rotating within ahousing 24 which carries a backing plate 26. Conventional brake shoemechanism, not shown, is mounted on the backing plate which remainsstationary. The structure, with the exception of the backing plateattachment, is generally applicable to the front wheels also.

Each rear wheel assembly is provided with a hub extending adapter 28,with lengthened studs 30 passing through the adapter. The wheel frame 32is secured on the extended studs by the usual lug nuts 34, and is thusmounted slightly outboard of its normal position. Secured between thewheel frame and adapter 28 is a drive disc 36, having a plurality ofsockets 38 near the periphery. Concentric with the adapter 28 is a pumpunit 40, having a cylindrical ring housing 42 which is supported frombacking plate 26 by support members 44. Any suitable arrangement ofbolts or other such fasteners may be used to make the pump unitdetachable for access to the brake mechanism. In the housing 42 is aring-like rotor 46, having a bearing flange 48 projecting from one facearound the inner periphery. The bearing flange 48 rides in an annularchannel 50 in the outboard face of housing 42, and isheld between innerand outer sealed bearings 52 and 54. Pump unit 40 may be a gear type,vane type, or other suitable hydraulic pump configuration, so nospecific structure has been shown for the rotor 46.

Mounted in the rotor 46 are drive pins 56 which can extend from bearingflange 48 and are spaced to fit into the sockets 38 of drive disc 36.Each drive pin has a head 58 which slides in a chamber 60, and is biasedinwardly to the retracted position by a spring 62. The drive pin isextended by fluid pressure supplied through a duct 64 which enters thechamber 60 on the opposite side of head 58 from spring 62. All ducts 64connect to an annular groove 66 in the outboard face of rotor 46, thegroove being aligned with a pressure inlet 68 in housing 42.

In each front wheel 18, a hydraulic motor 70 is mounted in a mannersimilar to pump 40. The motor is substantially similar to the pump,including the drive pins 56 which engage sockets 38 in a drive disc 36,the similar parts being correspondingly numbered in FIG. 3. Thedifference lies in the rotor 72, in which "the ducts 74 supplyingactuating pressure to the drive pin chambers 60 lead from the pressurechamber "76 of the motor, rather than from an external source, as in theIn the installation, each pump 40 is connected by flexible hoses 78 and80 to a selector valve 82, from which a pressure line 84 and a returnline 86 extend to the front wheel and are coupled to t the associatedmotor 70 by flexible hoses 88 and 90, respectively. From selector valve82 another pressure line 92 and return line 94 lead to a connectingblock 96 mounted on the rear of the vehicle. By installing hydraulicmotors in the wheels of a trailer to be towed by the vehicle, thetrailer wheels can also be driven by coupling their motors to connectingblock 96. Hydraulic fluid would have to be added to fill the system whena trailer is coupled and, when not in use, the connections on theconnecting block would be capped to prevent leakage. The selector valve82 is a conventional two-way valve capable of switching the hydraulicconnections from the pump to either the vehicle or the trailer. Eachselector valve has an actuating lever 98 connected by a control rod 100to suitable driver operated control means, not shown. Fluid level in thesystem is maintained from a reservoir 102, which is illustrated as beingconnected by supply lines 104 to the selector valves 82, but could beconnected to any other convenient point in the system.

The system is operated by control valve 110 mounted for convenientaccess to the driver. Control valve 110 comprises a body 112 with a pairof parallel cylindrical chambers 1 14, in which are slidable valveelements 116 with O-ring seals 118. The valve elements are actuated by acam 120 on a lever 122, the cam driving a pair of pistons 124 mounted inan end cap 126 of the valve body. Load springs 128 between the pistons124 and valve elements 116 apply a controlled pressure to drive fluidout through ports 130 and past check valves 132, to outlets 134 in a cap136 on the other end of the body. Outlets 134 are connected by pressurelines 138 and flexible hoses 140 to the pressure inlets 68 of thehydraulic pumps 40. Return springs 142 lift the valve elements 116 whenthe cam 120 is released, allowing fluid to bleed back through ducts 144around the check valves 132 and through an exhaust outlet 146, which isconnected to reservoir 102 by a return line 148.

The fluid system is a completely closed circuit and all air iseliminated. With the auxiliary drive inoperative, the pumps and motorsare stationary and have no coupling with the wheels, so there is no dragon the normal drive means. To actuate the system, lever 122 is moved todepress valve elements 116 and cause fluid pressure to be applied todrive pins 56 in the pumps 40. The drive pins are extended and engagesockets 38 in drive discs 36, so coupling the rotors 46 to the drivenwheels 12. Pumps 40 apply pressure to motors 70, the initial pressurecausing drive pins 56 to be extended and engage the drive discs,coupling the motors to the front wheels 18. The front wheels are thusdriven by direct hydraulic coupling to the rear wheels, all four wheelsbeing driven at the same speed, in forward or reverse direction.

To disengage the four wheel drive, lever 122 is moved to release cam 120and allow valve elements 116 to be lifted by return springs 142.Pressure is then relieved through ducts 144 and exhaust port 146,allowing all the drive pins 56 to be retracted by their springs 62 anddisconnect the drive couplings with the wheels. Since the system isclosed and the fluid volume constant, the hydraulic fluid itself can beused for the control operation. The valve unit 110 is designed so thatthe displacement of valve elements 116 is essentially equal to the totaldisplacement volume of all the drive pin chambers. Drive engagement isthus maintained as long as cam 120 holds the valve elements depressed,avoiding the necessity for separate control means and possible leakage.The load springs 128 and drive pin return springs 62 prevent occurrenceofa hydraulic lock which could overload the system.

Having described my invention, I now claim.

1. A hydraulic auxiliary drive system for a vehicle having driven wheelsand non-driven wheels, the system comprising:

a hydraulic pump mounted on each of said driven wheels;

a hydraulic motor mounted on each of said nondriven wheels;

closed fluid conducting circuit means interconnecting each pump with anassociated motor on the same side of the vehicle;

each pump and motor having a selectively operable driving connectionwith the respective wheel;

and control means for selectively engaging and disengaging the drivingconnections of said pumps and motors with the respective wheels.

2. The system according to claim 1 and including:

an external coupling connector block mounted on the vehicle with fluidconducting means connected to said pump;

and a selector valve in said fluid conducting circuit means forselectively conducting fluid to said motor and said connecting block.

3. The system according to claim 1, wherein each of said pumps comprisesa ring-like housing concentric with and fixed relative to the respectivewheel, and a rotor in said housing;

a drive disc secured to the wheel to rotate therewith and having socketstherein;

and said control means including drive pins connected to said rotor, andmeans to extend said drive pins to engage said sockets and couple therotor and drive disc.

4. The system according to claim 3, wherein said drive pins are slidablymounted in said rotor and biased to retracted position therein;

said means to extend comprising fluid pressure means coupled to thefluid in said pump for extending said drive pins;

and actuating means for applying initial pressure to the fluid in saidpump to extend the drive pins.

5. The system according to claim 4, wherein said actuating meansincludes a control valve in said closed fluid conducting circuit means,said valve having piston means movable to displace sufficient fluid inthe closed circuit to hold said drive pins in extended position.

6. The system according to claim 5, wherein each of said motorscomprises a ring-like housing concentric with and fixed relative to therespective wheel and a rotor in said housing;

a drive disc secured to the wheel to rotate therewith,

and having sockets therein;

and said control means including drive pins connected to said rotor, andmeans to extend said drive pins to engage said sockets and couple thelast mentioned rotor and the associated drive disc.

7. The system according to claim 6, wherein said last mentioned drivepins are slidably mounted in the motor rotor and biased to retractedposition therein;

said means to extend comprising fluid pressure means coupled to thefluid in said motor.

8. The system according to claim 1, wherein said closed fluid conductingcircuit means has a constant volume of fluid completely filling thecircuit;

said driving connections being operable by fluid pressure in the circuitfor coupling said pumps and motors with the respective wheels;

ing means therein, the drive connecting means in said motors beingactuated by fluid pressure generated therein by said pumps.

10. The system according to claim 8, and including a lever connected tosaid piston means for holding the same in the pressurizing position.

1. A hydraulic auxiliary drive system for a vehicle having driven wheelsand non-driven wheels, the system comprising: a hydraulic pump mountedon each of said driven wheels; a hydraulic motor mounted on each of saidnon-driven wheels; closed fluid conducting circuit means interconnectingeach pump with an associated motor on the same side of the vehicle; eachpump and motor having a selectively operable driving connection with therespective wheel; and control means for selectively engaging anddisengaging the driving connections of said pumps and motors with therespective wheels.
 2. The system according to claim 1 and including: anexternal coupling connector block mounted on the vehicle with fluidconducting means connected to said pump; and a selector valve in saidfluid conducting circuit means for selectively conducting fluid to saidmotor and said connecting block.
 3. The system according to claim 1,wherein each of said pumps comprises a ring-like housing concentric withand fixed relative to the respective wheel, and a rotor in said housing;a drive disc secured to the wheel to rotate therewith and having socketstherein; and said control means including drive pins connected to saidrotor, and means to extend said drive pins to engage said sockets andcouple the rotor and drive disc.
 4. The system according to claim 3,wherein said drive pins are slidably mounted in said rotor and biased toretracted position therein; said means to extend comprising fluidpressure means coupled to the fluid in said pump for extending saiddrive pins; and actuating means for applying initial pressure to thefluid in said pump to extend the drive pins.
 5. The system according toclaim 4, wherein said actuating means includes a control valve in saidclosed fluid conducting circuit means, said valve having piston meansmovable to displace sufficient fluid in the closed circuit to hold saiddrive pins in extended position.
 6. The system according to claim 5,wherein each of said motors comprises a ring-like housing concentricwith and fixed relative to the respective wheel and a rotor in saidhousing; a drive disc secured to the wheel to rotate therewith, andhaving sockets therein; and said control means including drive pinsconnected to said rotor, and means to extend said drive pins to engagesaid sockets and couple the last mentioned rotor and the associateddrive disc.
 7. The system according to claim 6, wherein said lastmentioned drive pins are slidably mounted in the motor rotor and biasedto retracted position therein; said means to extend comprising fluidpressure means coupled to the fluid in said motor.
 8. The systemaccording to claim 1, wherein said closed fluid conducting circuit meanshas a constant volume of fluid completely filling the circuit; saiddriving connections being operable by fluid pressure in the circuit forcoupling said pumps and motors with the respective wheels; said controlmeans including actuating means for applying initial pressure in thecircuit, comprising a control valve in the circuit having piston meansmovable to displace a volume of fluid sufficient to engage said drivingconnections.
 9. The system of claim 8, wherein said control valve iscoupled to said pumps to actuate the drive connecting means therein, thedrive connecting means in said motors being actuated by fluid pressuregenerated therein by said pumps.
 10. The system according to claim 8,and including a lever connected to said piston means for holding thesame in the pressurizing position.